How to connect 20 fans?

I want to plugin 20 fans. On my motherboard (Asus Z10PE-D8 WS) there are 2 cpu fan 4 pin connectors and 7 other 4 pin connectors. So 9 fans are ok, but 11 more. The case is Corsair 900D and psu: Corsair AX1200i. There are 20 fans because 8 will be on radiators.

What fan controller and splitters should i buy? The worst thing is that i don't want any controller which is visible form outside in 3,5 or 5,25 bay, it should sit inside hidden like new Corsair Link Commander Mini which will never be available to buy in my country.